---
id: CVE-2026-93558
title: A flaw was found in Netty's WebSocketServerExtensionHandler
summary: >-
  A flaw was found in Netty's WebSocketServerExtensionHandler. A remote,
  unauthenticated attacker can exploit this vulnerability by using HTTP/1.1
  pipelining to send requests faster than the application can respond. This
  leads to an unboun…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-1035
vendor: Red Hat
product: netty-codec-http
affected:
  - netty-codec-http (all versions)
  - netty-codec-http (all versions)
  - netty-codec-http (all versions)
  - netty-codec-http (all versions)
  - netty-codec-http (all versions)
  - netty-codec-http (all versions)
  - netty-codec-http (all versions)
  - netty-codec-http (all versions)
  - netty-codec-http
  - netty-codec-http
  - netty-codec-http (all versions)
  - netty-codec-http (all versions)
published: '2026-09-18'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T23:17:08.123'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-93558'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2026:69440'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:69470'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:70257'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/security/cve/CVE-2026-93558'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2536932'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2536932'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-93558.json
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-93558'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-93558'
tags:
  - nvd
  - cve.org
  - exploit-available
  - csaf
  - vex
  - red-hat
epss: 0.00702
epssPercentile: 0.51839
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-18T14:54:07.542588Z'
ingestedAt: '2026-09-18T14:43:13.072Z'
---

## Overview

A flaw was found in Netty's WebSocketServerExtensionHandler. A remote, unauthenticated attacker can exploit this vulnerability by using HTTP/1.1 pipelining to send requests faster than the application can respond. This leads to an unbounded growth of a per-connection queue, consuming excessive memory. Eventually, this can cause the Java Virtual Machine (JVM) to exhaust its heap, resulting in a Denial of Service (DoS) for the affected server.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat AMQ Broker 7, Red Hat AMQ Clients, Red Hat build of Apache Camel 4 for Quarkus 3, Red Hat build of Apache Camel for Spring Boot 4, Red Hat build of Apicurio Registry 3, Red Hat build of Debezium 3, … · no fix planned: Red Hat Fuse 7, Red Hat JBoss Enterprise Application Platform 7, Red Hat Single Sign-On 7, Red Hat AMQ Broker 7, … · updated 2026-09-22 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-93558.json)